April 29, 2004 Edward Barnard Elizabeth Hager Kevin McComber Jenny Lichter

Overview Goal Etchants Volume Fraction Infiltration!! Backfilling a Preform Increasing Volume of Tin-Lead Future Plans Gantt Chart

Tin-Lead Etchants Ethanol Nital –1% solution –Approximately 45 seconds –Revealed grain structure of metals

Volume fraction Why we care: –High pressure in our process can potentially allow for the the infiltration of higher volume fraction of ceramic particles –Yields hard, lightweight materials with good fracture toughness properties Determined by –Theoretical calculations –Optical imaging and image processing

Calculating Volumes and Average Density r = (1/6)*h+(1/2) r h Volume = 2*(19π/32) h = 1.5 in Volume = (4/3)(π)(0.5 3 )= 0.52 Volume = 4.25 Calculating volume fraction: - weigh part - MMC weight = part weight – (  tin lead )*(V tin lead ) - (  ceramic )*(V ceramic ) + (  tin lead )*(1-V ceramic ) = MMC V ceramic = 70 % for sintered SiC, 120 grit

Preparation and Imaging Tried to cut with hacksaw, band saw –Was too hard!! Cut with diamond-coated wheel Polished to 4000 grit –Scratches still remained –Scratches confuse volume fraction calculations based on images from optical microscope –Thus very good polishing necessary Imaged with optical microscope

Image Processing Used MATLAB Set threshold brightness to section image into matrix and ceramic Integrate and average over many images to get average area fraction For isotropic materials: Area Fraction = Volume Fraction

Infiltrated Al 2 O 3 Preform Alumina = 39 %

Infiltrated SiC preform % Ceramic

Backfilling a Preform Backfilling important for complicated shapes Our plan: insert plate to demonstrate backfilling Backfilling: red arrows

Increasing metal Alter runner setup to accommodate metal Sn- Pb Mold

Future plans Further optical imaging –Fracture behavior –Volume fraction As already mentioned –Backfilling –Increasing metal Final Prototype

Gantt Chart